The prickles on the leaves and fruiting capsules can cause mechanical injury to humans and grazing animals (Oakes and Butcher 1962). The acrid yellow sap has slightly corrosive properties (Dalziel 1937, Quisumbing 1951) and the plant can cause dermatitis in some individuals (Behl et al. 1966). Patch tests carried out using the leaves of this species crushed in a small quantity of normal saline elicited positive reactions in 2 of 20 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978).

Stuart (1911) noted that in Chinese traditional medicine, the oil expressed from the seeds of this plant (which is known as Lao Shu Le) is said to allay the irritation of herpes and many other eruptions of the skin. The seed is a common adulterant of mustard seed (Brassica) either by chance or for profit. Ingestion of argemone seed oil has caused epidemic dropsy in humans in Africa and India with hyperpigmentation of the skin and "sarcoidal" angiomatous swellings and glaucoma (Watt & Breyer-Brandwijk 1962).

Berberine, one of the alkaloids derived from the plant, produces intense pain when infiltrated into the conjunctiva for the treatment of trachoma or into the skin for the treatment of leishmaniasis (Watt & Breyer-Brandwijk 1962). Berberine, when injected as a local anaesthetic, occasionally produces hyperpigmentation at the site of injection (Seery and Bieter 1940). Reactions to berberine are also noted under Berberis.

Argemone platyceras Link & Otto

Rough Prickly Poppy, Thistle Poppy

This species can produce mechanical injury (Muenscher 1951).

Argemone subalpina McDonald

McDonald (1991) described this spiny species from subalpine regions of Sierra Peña Nevada, Mexico as being closely related to Argemone platyceras Link & Otto (see above).

Bocconia sp.

Injection of an extract of the plant produces local anaesthesia but there is also an irritant effect (Martinez 1969).

Chelidonium majus L.

Tetterwort, Greater Celandine, Rock Poppy

Dioscorides (1st Century A.D.) referred to a bitter and biting nature of the plant. According to Wren (1975) the fresh juice makes an excellent application for corns and warts, and an infusion of the herb has been used orally in the treatment of jaundice, scrofulous diseases and eczema. In Chinese traditional medicine, the dried whole plant (known as Bai Qu Cai) is applied externally in the form of an ointment or paste to treat insect bites and infections (Huang 1993).

The fresh juice - which is bright orange in colour - when applied to the skin, is acrid, irritant and vesicant, and even escharotic (Loudon 1855, Van Hasselt 1862, Oesterlen 1856, US Dispensatory 1884, Cheney cited by White 1887, Piffard 1881). According to North (1967) the plant, which is commonly found near old walls and ruins in most parts of England and Wales, can produce dermatitis. Hardin and Arena (1974) also refer to dermatitis from the plant in the US and Canada. The sap of the plant is also irritating to the eye (Hilbert 1916) but was at one time used to treat opacities of the cornea to improve eyesight.

The plant contains a variety of alkaloids including chelidonine, chelerythrine, and berberine, and also chelidonic acid. Chelidonic acid is an acrid irritant which has been used to treat warts. Repeated subcutaneous injections for the treatment of an epithelioma of the eyelid produced much reaction and pain after each injection and the lids sloughed and scarred up to the orbital margin (Duke-Elder & MacFaul 1972b).

The genus is monotypic. The plant is botanically unrelated to the lesser celandine, Ranunculus ficaria L., fam. Ranunculaceae.

Opium, the dried latex of the unripe capsule, yields about 20 alkaloids including morphine. Contact dermatitis occurred in a worker in a morphine factory who had washed some cloths through which morphia had been filtered (Lewin 1908), and in nurses who made morphine tablets (Dore and Thomas 1944, Jordon and Osborne 1939). Crude morphine produced dermatitis in factory-workers and patch tests with morphine hydrochloride produced negative results (Dore and Thomas 1944, Green 1944). Morphine itself has produced strong sensitivity; a nurse showed a positive patch test reaction to morphine solutions diluted to 1 in 1,000,000 and exposure to the air in a ward produced clinical symptoms (Jordon and Osborne 1939). Ethylmorphine can cause dermatitis of the eyelids (Duke-Elder 1965, Cummer 1931). Opium applied to the skin caused dermatitis of the genitals (Heller 1931). Contact dermatitis from morphine or its unidentified impurities is most likely to occur at the factory level where mechanical handling is avoided and the compounds are worked largely by hand. Panniculitis can occur in morphine addicts (Lopez et al. 1961).

The plant was cultivated as a source of cooking oil by Egyptians as early as 1500 B.C. The seed which is free of narcotic properties provides oil and the treated seed is used as a condiment for poppyseed cake and bread.

Roemeria hybrida DC.

(syn. Chelidonium hybridum Medik., Roemeria violacea Medik.)

Purple Horned Poppy

Roemeria violacea has irritant properties (Pammel 1911).

Sanguinaria canadensis L.

Blood Root, Red Puccoon, Tetterwort

The genus Sanguinaria L. comprises this single species, which is found growing naturally in eastern North America (Mabberley 1987). The name sanguinaria refers to the fact that the plant, when wounded, throws out a copious blood-like sap - a property well known to the American Indians, who used the red sap as a dye (Felter & Lloyd 1898).

The rhizome of this plant provides Sanguinaria, which was formerly included in both British and US Pharmacopeias. According to Felter & Lloyd (1898), the dried and powdered root, when inhaled, is exceedingly irritant to the nasal passages and provokes sneezing - this property evidently contributing in some way to its reported use as a snuff for the treatment of nasal polyps. Felter & Lloyd (1898) also state that: "Sanguinaria is of value in syphilitic skin eruptions, and, as an ointment, has been employed, locally, in tinea. The powder, made into a cataplasm with slippery-elm, has been used in domestic practice as a local dressing for frozen feet. An infusion, made in vinegar, has been found valuable in several cutaneous diseases, as eczema, ringworm, and warts. At one time the root was extensively employed in the treatment of carcinomata, and was also applied to exuberant excrescences for its escharotic action, and to ill-conditioned ulcers, to create a healthy energy in the sores." Both Wren (1975) and Stuart (1979) allude to these early uses.

A female laboratory worker developed a vesicular eruption on the fingers, face, neck and chest one day after handling Sanguinaris powder. It is possible that she had been exposed to poison ivy (Toxicodendron) three days previously (Fox 1921).